Conventional laser printing systems as laser printers and selective-laser melting machines consist of a single high-power laser and a scanner to scan the laser over the area to be illuminated. To increase the processing speed, it is desirable to have a printing head with several independent channels i.e. an addressable array of lasers covering a significant part of the area. Preferably, the printing head covers the full width of the area to be printed with one addressable laser source per pixel, so that the print head needs to be moved only in one direction. The requirements regarding the electrical power which has to be provided depend on the width of the printing head, number and power of the laser sources per pixel and the structure which has to be printed. In extreme cases several kilowatt of electrical power at several thousand Ampere of electrical current have to be provided if a close surface has to be processed.
US 2014/0139607 A1 discloses an optical writing device is configured to form electrostatic latent images on a plurality of photosensitive elements by a plurality of light sources. The optical writing device includes: an image-data acquiring section that acquires image data; and a light-source control section that performs light-emission control on the light source based on pixel data generated from acquired image data, and also performs a neutralization process on the photosensitive element by controlling the light source to expose the photosensitive element to light. In the neutralization process, the light-source control section divides a period during which light-on/off control can be performed on the light source, into sub-periods based on pixel data input to the light-source control section, and causes the light sources to be lit in any one of the sub-periods so as to always place at least one of the plurality of light sources in a light-off state.
WO 2011/114296 A1 discloses a laser based printing apparatus using laser light sources for supplying energy to a target object to form an image, comprising a laser light source arrangement comprising a plurality of laser light sources, a transport mechanism and a controlling arrangement connected to the laser light arrangement and the transport mechanism.
WO 2015/091459 A1 discloses a laser printing system for illuminating an object moving relative to a laser module of the laser printing system in a working plane is provided. The laser module comprises at least two laser arrays of semiconductor lasers and at least one optical element. The optical element is adapted to image laser light emitted by the laser arrays, such that laser light of semiconductor lasers of one laser array is imaged to one pixel in a working plane of the laser printing system and an area element of the pixel is illuminated by means of at least two semiconductor lasers.